The present invention concerns a fuel injector for operation with combustible gas. The fuel injector may in particular be formed as a dual-fuel injector.
Gaseous fuels are increasingly gaining importance in the (large) engine sector, in particular in stationary engines for power generation. Natural gas for example, because of its excellent availability and favorable emission potential in comparison with diesel fuel, is ideally suited for economic and environmentally friendly engine operation.
In fuel injectors which are formed as multiple substance injectors or dual-fuel injectors, and as well as the gas injector part also comprise a liquid fuel injector part, in particular for an ignition jet operation, the gas nozzle openings of the fuel injector are often not distributed over the complete circumference of the fuel injector, see for example publication US 2014/0091159 A1. Especially in injectors which have several gas nozzle needles arranged for example around one central liquid-fuel nozzle needle, often a gas nozzle assembly is assigned to a gas nozzle needle; in this assembly, the gas nozzle openings radially cover only a part of 360°, for example in the case of four gas nozzle needles, each covers 90°.
However, such fuel injectors, the nozzle needles of which are received as standard in respective rotationally symmetrical bores, entail the disadvantage that flow losses of combustible gas occur because of the asymmetric flow around the needle seat.